Various objects, including mineral resources such as iron ore and limestone, are conveyed by a conveyor belt. When being conveyed by the conveyor belt, the objects to be conveyed are fed onto an upper rubber cover of the conveyor belt from a hopper or another conveyor belt. The fed objects to be conveyed are loaded on the upper rubber cover and conveyed in a traveling direction of the conveyor belt. Here, the upper rubber cover is subject to wear as a result of the objects to be conveyed sliding on the upper rubber cover. When a conveyor belt with reduced tolerance strength due to wear caused by the objects to be conveyed is continuously used, the conveyor belt may sever, forcing the cessation of operations. For repairs, great amounts of time and costs are required. To prevent such problems, technologies for detecting the wear condition of conveyor belts are known (see for example Japanese Unexamined Patent Application Publication No. 2010-52927A).
However, conventional technologies that detect the wear condition while the conveyor belt is running suffer from sensor errors when detecting the amount of wear caused by vibrations of the running conveyor belt. Thus, the wear condition of the upper rubber cover of the conveyor belt is unable to be detected with a sufficient accuracy.